Teleconferences and video conferences are becoming ever more popular mechanisms for communicating. Many portable computer devices, such as laptops, netbooks, and smartphones, today have built-in microphones. In addition, many portable computer devices have built-in cameras (or can easily have an inexpensive external camera, such as a web cam, added). This allows for very low cost participation in teleconferences and video conferences.
It is common for participants in a conference to be typing during the conference. For example, a participant may be taking notes about the conference or multi-tasking while talking or while listening to others talk. With the physical proximity of the keyboard on the portable computer device to a microphone that may also be on the portable computer device, the microphone can easily pick up noise from the keystrokes and transmit the noise to the conference, annoying the other participants.
In headphones, it is common to remove unwanted ambient noise by building a model of the noise, and inserting the “inverse” of that noise in the audio signal to cancel the noise. The trick is to build a model that accurately matches the noise so that it can be removed without removing meaningful parts of the audio signal. For example, noise canceling headphones have small microphones outside the headphones themselves. Any sounds the headphones detect as coming from “outside” are potentially noise that should be canceled.